(1) Field of the Invention
The present invention relates to a knowledge-based system which performs reasoning processes by the use of many kinds of knowledge. More particularly, it relates to a knowledge-based system which includes a plurality of reasoning processors each having a knowledge base and in which each of the reasoning processors executes a reasoning process of its own while utilizing a result reasoned by another reasoning processor, according to the circumstances.
(2) Description of the Prior Art
Knowledge-based systems have come into the limelight as an approach effective for processing using a computer to solve a problem which is difficult to state by conventional procedural programming techniques wherein the sequence of use of all items of knowledge is completely stipulated by a control process. For example, a problem as to which the experience or perception of a skilled hand or expert forms part of resolving means.
The feature of the knowledge-based system consists of a knowledge which base for storing special knowledge is isolated from a program (reasoning mechanism) for resolving problems by the use of the knowledge, whereby the addition of new knowledge to the knowledge base and the change of the content of the knowledge already registered can be carried out independently of the program. That is, the knowledge-based system does not embed knowledge in the control process as in the conventional procedural programming, but it handles the knowledge as a simple data base. It is therefore advantageous in that, even when the whole aspect of knowledge for finishing up a system or the mutual relations of individual items of knowledge is/are unclear, software can be constructed by successively adding local or fragmentary items of knowledge to the knowledge base. The knowledge to be stored in the knowledge base includes, for example, rule type knowledge consisting of if-parts and then-parts, and fact type knowledge descriptive of facts corresponding to the if-parts.
Prominent as the examples of systems developed according to the knowledge base approach are "XCON" and "XSEL" by Digital Equipment Corp., "DIPMETER ADVISOR" by Schumberger Inc., and "YES/MVS" by IBM Inc.
All of the developed examples noted above, however, has computerized expertise or experience only in a very narrow field. At present, there has not been developed a large-scale knowledge base (the total number of items of knowledge reaches the order of 10.sup.3 -10.sup.4) for reasoning with many kinds and large amounts of knowledge as can be put into practical use in the field of, for example, monetary business. As causes therefor, it is mentioned that the processing time lengthens with increase in the amount of knowledge, so a practical reasoning ability is not attained, and further that a problem resolving program (reasoning mechanism) which allows knowledge expressions in many forms has not been developed.